CONTROL DEVICE FOR HYDRAULICALLY DRIVEN TOOL

Title:

CONTROL DEVICE FOR HYDRAULICALLY DRIVEN TOOL

Document Type and Number:

WIPO Patent Application WO/1997/045252

Kind Code:

A1

Abstract:

When a start switch (SW3) is depressed, a one-shot multivibrator circuit (15) is actuated to output one pulse. When the pulse enters a self-holding circuit (16), the self-holding circuit (16) is self-held to output an H-level signal until reset. As a result, a transistor (17) is turned on to actuate a relay (R1) for lowering a ram. When the ram reaches the lower limit position, a lower limit switch (LS4) is opened, so that a signal from a one-shot multivibrator circuit (18) causes a self holding circuit (21) to self-hold an H-level signal. The signal is delayed by a delay circuit (22) to turn a transistor (23) on. Therefore, a relay (R2) for raising the ram is actuated. Restarting will not be effected due to the operation of the one-shot multivibrator circuit (15) even when the start switch is kept depressed. Also, the service life of a valve changeover mechanism can be extended owing to the operation of the delay circuit (22). Further, erroneous operations can be prevented by operations of a delay circuit (19) and an AND circuit (24) even when the lower limit switch (LS4) chatters.

Inventors:

SHIMADA KEISUKE (JP)
SHOJI MICHIHIRO (JP)

Application Number:

PCT/JP1997/000879

Publication Date:

December 04, 1997

Filing Date:

March 18, 1997

Export Citation:

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Assignee:

NITTO KOHKI CO (JP)
SHIMADA KEISUKE (JP)
SHOJI MICHIHIRO (JP)

International Classes:

B21D28/24; B30B1/32; B30B15/16; B30B15/18; F15B21/08; (IPC1-7): B30B15/18; B30B1/32; B21D28/20

Foreign References:

JPS5923920B2

1984-06-05

Other References: